/*
 * Alloy Analyzer
 * Copyright (c) 2002 Massachusetts Institute of Technology
 *
 * The Alloy Analyzer is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * The Alloy Analyzer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with the Alloy Analyzer; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package alloy.ast;

/** Represents a declaration <pre>var = expr</pre> associated with a let. */
public class LetDecl extends TreeNode {

    private static final int VAR_INDEX = 0;
    private static final int EXPR_INDEX = 1;

    public LetDecl(Location location_, Variable var_, Expr expr_) {
        super(location_, var_, expr_);
    }

    public LetDecl(Variable var_, Expr expr_) {
        this(Location.UNKNOWN, var_, expr_);
    }

    /** get the var of this. */
    public Variable getVar() {
        return (Variable)childAt(VAR_INDEX);
    }

    /** set the Var of this */
    public void setVar(Variable newChild_) {
        setChild(VAR_INDEX, newChild_);
    }

    /** get the expr of this. */
    public Expr getExpr() {
        return (Expr)childAt(EXPR_INDEX);
    }

    /** set the Expr of this */
    public void setExpr(Expr newChild_) {
        setChild(EXPR_INDEX, newChild_);
    }

    /**
     * accept an AST visitor
     * @param visitor_ the visitor
     */
    protected void acceptVisitor(ASTVisitor visitor_) {
        visitor_.visit(this);
    }

    /**
     * accept a returning AST visitor
     * @param visitor_ the visitor
     * @return the Object returned by the visitor
     */
    protected Object acceptReturnVisitor(ASTReturnVisitor visitor_) {
        return visitor_.visit(this);
    }

    public String nodeString() {
        return getVar().nodeString() +
        " = " + getExpr().nodeString();
    }
}
